Conventional machines of the type described above, which are virtually 100% in use to date, are without exception multi-station machines. One workstation is arranged next to the other and the yarn feed devices and winding devices are driven by continuous shafts, which run lengthwise through the machine and are centrally driven by central electric motors arranged at the end.
The spindles are generally driven by belts or bands or else, in machines of a more recent design, are made to rotate by individual motors seated below or next to the spindles. In both cases, the drive or the feed and control take place centrally and collectively for all the spindles equally.
The machine frames are configured in double-sided sections in the mode of construction that is conventional nowadays, which contain about 8 to 16 spindles in each case and are sent to the customer disassembled, fully operable. They are assembled there with a central control and drive unit to form complete machines of up to about 40 meters in length, not infrequently with more than 200 workstations. These concepts and the high number of centrally provided spindles have meant that the entire production, transport and assembly costs can be apportioned very favourably to the individual workstations. This is therefore, overall, a very economical solution.
Machines of this type of design are, however, only suitable for the efficient production of mass produced goods. The flexibility required for smaller batches is not, on the other hand, ensured. Tasks requiring a high degree of flexibility can only be performed with high outlay for modification or with machines that are only used to part of their capacity, in other words relatively expensively.
A further drawback of centrally driven machines is that the efficiency of the machines drops dramatically in the case of machine malfunctions, because a large number of spindles are immediately affected during the machine stoppage. Each machine malfunction therefore becomes a relatively expensive event. Reference is made to German Patent Publication DE 29 25 668 A1 by way of example for a two-for-one twisting machine having the properties mentioned. Each so-called field, which consists of a large number of workstations, is arranged there between vertical machine stands and forms one section.
Proceeding from this, there has always been the requirement for more flexible machines. However, this generally failed owing to the comparatively high costs for producing the machines.
One possibility of achieving more flexibility is disclosed, for example, in European Patent Publication EP 1 737 775 A1. The solution described there still basically has the structure of a conventional multi-station machine, but individual drives and individual controls are now allocated to the individual spindles/workstations instead of central drives. This means that each workstation can be operated virtually self-sufficiently. However, the drawback in this solution clearly remains the retention of the central machine structure. In other words, despite higher costs with regard to the available number of spindles, only a limited flexibility is produced for the user. Solution proposals for transporting the bobbins away or for heat extraction remain completely open in European Patent Publication EP 1 737 775 A1.
A further step in the direction of unlimited flexibility is documented by European Patent Publication EP 1 357 208 A1. A self-sufficient individual workstation of a two-for-one twisting machine with precision winding-on is described here. A plurality of units thereof can still be joined to form a type of multi-station machine, but each position is nevertheless fully self-sufficient and is driven separately from the others. Any possibility of collecting the finished bobbins by a corresponding transporting device is also missing here. Only a one-sided machine is shown and described here, in which, however, any desired arrangement of the individual spindle units, also including a completely separate installation, is left open.
In order to be able to reduce the high costs for the obligatory air conditioning in textile businesses, conventional machines are furthermore frequently designed such that the machine frame toward the centre of the machine, forms a channel system, via which hot air can be extracted before the room is affected. A possibility of this type is neither provided nor structurally conceivable in the solution approach according to European Patent Publication EP 1 357 208 A1. A stand-alone machine frame standing independently for each position, inevitably leads to higher production costs. The stability of the individual spindle unit is limited by its base area. It is therefore necessary to take additional measures to increase the stability, said specification teaching that the individual spindle units are to be connected to one another.
It is furthermore known from European Patent Publication EP 0 384 092 B1, to produce double spindle units instead of individual spindles. These double spindle units have the advantage of greater stability and contain a removal system for the bobbins to be handled. The described double spindle units are seated in a base framework, which has six vertical struts spaced apart from one another, which are in turn connected to one another at the top and bottom by cross-members. The working elements of the two workstations are then fastened to this complex frame formed from a plurality of spatially arranged frameworks. The complex frame construction, as in conventional multi-station textile machines, only permits an extraordinarily limited variation of the dimensions of the working elements.